Illuminator for emitting at least two lights having directivity and display apparatus using same

ABSTRACT

A display apparatus includes a liquid crystal display panel and an illuminator disposed at the back of the panel for emitting at least two illumination lights having directivities in different directions toward the panel. The illuminator includes a light guide plate made of transparent material whose one end surface serves as a light entrance end surface, whose one plate surface serves as a light exit surface, and whose other plate surface serves as a light direction changing surface for changing the advancing direction of light entering from the light entrance end surface. The light direction changing surface has a plurality of circular-arcing slanted surfaces shaped into semicircles formed on concentric circles centered at the center of the longer dimension of the light entrance end surface. Light emitting elements are disposed on the light entrance end surface at two positions on left and right sides of the center equidistantly apart therefrom.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional Application of U.S. applicationSer. No. 11/391,915 filed Mar. 29, 2006 now U.S. Pat. No. 7,518,593,which is based on Japanese Patent Application No. 2005-101973 filed onMar. 31, 2005, which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an illuminator for emitting lightshaving directivity in at least tow directions, and a display apparatuswhose display panel is backed by this illuminator.

2. Description of the Related Art

Conventionally, edge-light type backlights have been known asilluminators for display panels. This type of backlight is built up of alight guide made of a transparent plate and a light source, wherein oneend surface of the light guide serves as a light entrance surface for alight from the light source to enter, and one plate surface of the lightguide serves as a light exit surface from which the light absorbed fromthe one end surface goes out, and wherein the light source is disposedso as to face the one end surface of the light guide. Light from thelight source is let into the light guide from the light entrance surfaceand guided inside the light guide while being repetitively reflected onthe light guide, so as to be let out from almost the entire surface ofthe light exit surface.

On the other hand, as a display apparatus using a display panel, thereis proposed an apparatus which displays two different images on onedisplay panel, one of which images is viewable when the display panel isviewed from the right hand side of the display panel, and the other oneof which images is viewable when the display panel is viewed from theleft hand side thereof.

Such a display apparatus is used for, for example, a car navigationsystem for displaying a navigation image when the display is seen fromthe driver's seat, while displaying a different video when the displayis seen from the front passenger's seat.

Such a display apparatus is also used for displaying two images having aparallax corresponding to the left and right eyes of the viewer on onedisplay, so as to let a right eye image, which is to be viewed from theright hand side of the display apparatus, be recognized by the right eyeof the viewer, and a left eye image to be viewed from the left hand sideof the apparatus be recognized by the left eye of the viewer, therebydisplaying a three-dimensional image.

Liquid crystal display apparatuses for displaying such three-dimensionalimages include an apparatus for displaying the left eye image by pixelson every other column while displaying the right eye image by pixels onevery other remaining column, and distributing the light from pixels onevery other column and the light from pixels on every other remainingcolumn toward the left and right eyes of the viewer respectively byusing a lenticular lens so that the left eye image and right eye imagereach the intended eyes (Unexamined Japanese Patent Application KOKAIPublication No. H7-005455), or an apparatus for making the images beviewed by the left eye and right eye of the viewer via a parallaxbarrier in which a plurality of stripe-shaped transmissive portions andlight opaque portions, which are parallel with the columns of pixels ofthe liquid crystal display panel, are disposed alternately (UnexaminedJapanese Patent Application KOKAI Publication No. H3-119889 andUnexamined Japanese Patent Application KOKAI Publication No.H10-268230).

However, since such a display apparatus for displaying two images on onedisplay panel displays one image by pixels on every other column of thedisplay panel and displays the other image by pixels on every otherremaining column, each image has a low resolution, therefore imageshaving a satisfactory image quality cannot be displayed.

Furthermore, a lenticular lens having a lens pitch corresponding to thepixel pitch of the display panel, or a parallax barrier having atransparency pitch corresponding to the pixel pitch needs to be disposedsuch that each lens unit or each transparent portion will be in apredetermined positional relation with respect to the pixels on eachcolumn of the display panel with sufficient precision, making thedisplay apparatus hard to manufacture.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an illuminator suitablefor a display apparatus which displays at least two images on onedisplay panel for making these images be perceived separately from theright hand side and left hand side of the display panel.

Another object of the present invention is to provide a displayapparatus which displays at least two images on one display panel formaking these images be perceived separately from the right hand side andleft hand side of the display panel.

Yet another object of the present invention is to provide a displayapparatus which can display a three-dimensional image having a highresolution thus high in image quality, and which can be manufacturedeasily.

To achieve the above objects, an illuminator according to a first aspectof the present invention comprises:

a light guide plate having:

-   -   a light entrance end surface, provided on one end surface of a        plate-like transparent material, from which a light from a light        source enters;    -   a light exit surface, provided on a plate surface intersecting        with the light entrance end surface, from which a light entering        from the light entrance end surface goes out as guided in a        predetermined direction;    -   an opposite surface, provided on the other plate surface        opposite to the light exit surface; and    -   a plurality of circular-arcing slanted surfaces, provided on        either the opposite surface or the light exit surface, and        forming circular-arcs concentric with a semicircle having its        center at substantially a center of a length of an edge of the        light entrance end surface intersecting with the light exit        surface, for emitting, from the light exit surface, lights        entering from at least two positions on the light entrance end        surface, which positions are apart from the center of the light        entrance end surface by a predetermined distance on both sides        of the center, by changing advancing directions of the lights to        directions inclined with respect to a vertical reference plane        at respective angles corresponding to the distance from the        center, of the positions from which the lights have entered, and        parallel with respective planes perpendicular to a horizontal        reference plane, where the vertical reference plane is a plane        perpendicular to both the light exit surface and the light        entrance end surface, and the horizontal reference plane is a        plane including a normal line of the light exit surface and        perpendicular to the vertical reference plane, and

first and second light emitting elements, disposed on the light entranceend surface of the light guide plate at positions on both sides of acenter, which is a center of a longer dimension of the light entranceend surface at which a center of curvature of arcs of thecircular-arcing slanted surfaces is defined, so as to be apart from thecenter by a substantially same distance, for entering illuminationlights into the light guide plate from the light entrance end surface.

According to the illuminator according to the first aspect, lightsemitted from the two light emitting elements can have their advancingdirections changed to be emitted as a light having a light intensitypeak in the left hand side with respect to the normal line of theilluminator and as a light having a light intensity peak in the righthand side with respect to the normal line. Thus, two illumination lightshaving strong directivities in directions in the left hand side andright hand side as seen from the observation side can be obtained fromone illuminator.

In the present illuminator, it is preferred that the circular-arcingslanted surfaces be constituted by a plurality of circular-arcingreflection surfaces formed on the opposite surface of the light guideplate, to have shapes of semicircular arcs formed plurally on concentriccircles centered at the center of a longer dimension of the lightentrance end surface, for reflecting a first light emitted from thefirst light emitting element disposed on the light entrance end surfaceto travel inside the light guide plate, so that the first light will beemitted from the light exit surface with its advancing direction changedto a first direction inclined at a predetermined angle with respect tothe vertical reference plane toward one side of the vertical referenceplane on the horizontal reference plane, and for reflecting a secondlight emitted from the second light emitting element disposed on thelight entrance end surface to travel inside the light guide plate, sothat the second light will be emitted from the light exit surface withits advancing direction changed to a second direction inclined at apredetermined angle with respect to the vertical reference plane towardthe other side of the vertical reference plane on the horizontalreference plane.

Alternatively, it is preferred that the circular-arcing slanted surfacesbe constituted by a plurality of circular-arcing refraction surfacesformed on the light exit surface of the light guide plate, to haveshapes of semicircular arcs formed plurally on concentric circlescentered at the center of the longer dimension of the light entrance endsurface, for refracting a first light emitted from the first lightemitting element disposed on the light entrance end surface to travelinside the light guide plate, so that the first light will be emittedfrom the light exit surface with its advancing direction changed to afirst direction inclined at a predetermined angle with respect to thevertical reference plane toward one side of the vertical reference planeand parallel with a plane perpendicular to the horizontal referenceplane, and for refracting a second light emitted from the second lightemitting element disposed on the light entrance end surface to travelinside the light guide plate, so that the second light will be emittedfrom the light exit surface with its advancing direction changed to asecond direction inclined at a predetermined angle with respect to thevertical reference plane toward the other side of the vertical referenceplane and parallel with a plane perpendicular to the horizontalreference plane. In this case, it is preferred that the illuminatorfurther comprise a prism sheet disposed outside the light exit surfaceof the light guide plate, for refracting a light emitted from the lightguide plate in a direction parallel with the horizontal reference plane,and it is further preferred that the prism sheet comprise a plurality ofcircular-arcing prisms formed to have shapes of semicircular arcs formedplurally on concentric circles centered at a point corresponding to thecenter of curvature of the circular-arcing slanted surfaces of the lightguide plate.

In the present embodiment, it is preferred that the illuminator comprisea reflection plate disposed outside the opposite surface of the lightguide plate, for reflecting a light emitted from the opposite surfacetoward the light guide plate.

It is preferred that the illuminator further comprise: a third lightemitting element, disposed correspondingly to the center of the lightentrance end surface of the light guide plate at which the center ofcurvature of arcs of the circular-arcing slanted surfaces is defined,for entering an illumination light into the light guide plate from thecenter of the light entrance end surface; and a light source drivecircuit for controlling lighting of the first and second light emittingelements and the third light emitting element, and the light guide platehave a plurality of circular-arcing slanted surfaces for emitting alight entering from the center of the light entrance end surface fromthe light exit surface, by changing an advancing direction of the lightto a direction parallel with the vertical reference plane. According tothe present illuminator, two illumination lights having strongdirectivities in directions in the left hand side and right hand side asseen from the observation side, and an illumination light having a highluminance in the front-forward direction can be selectively emitted fromone illuminator.

Further, it is preferred that the illuminator further comprise: fourthand fifth light emitting elements, disposed on the light entrance endsurface of the light guide plate, on external sides of the first andsecond light emitting elements respectively, so as to face each other atpositions at substantially an equal distance from the center at whichthe center of curvature of the arcs of the circular-arcing slantedsurfaces is defined, for entering illumination lights into the lightguide plate from the light entrance end surface; and a light sourcedrive circuit for controlling lighting of the first and second lightemitting elements and the fourth and fifth light emitting elements. Inthis case, two illumination lights having strong directivities indirections in the left hand side and right hand side as seen from theobservation side and having a broad range of view can be obtained fromone illuminator.

It is further preferred that the illuminator further comprise ananisotropic dispersion plate, disposed outside the light exit surface ofthe light guide plate so as to face the light exit surface, fordispersing a light emitted from the light exit surface, in directionsinclined at predetermined angles within a predetermined range of angles,with respect to the vertical reference plane on the horizontal referenceplane. Also in this case, two illumination lights having strongdirectivities in directions in the left hand side and right hand side asseen from the observation side and having a broad range of view can beobtained from one illuminator.

A display apparatus according to a second aspect of the presentinvention comprises

(1) a display panel having a display area on which a plurality of pixelsare arranged in a matrix, for displaying at least one image by theplurality of pixels when a display signal corresponding to image datafor displaying an image is supplied to each of the plurality of pixels,

(2) an illuminator disposed at a back of the display panel andcomprising

-   -   (i) a light guide plate having:        -   a light entrance end surface, provided on one end surface of            a plate-like transparent material, from which a light from a            light source enters;        -   a light exit surface, provided on a plate surface            intersecting with the light entrance end surface, from which            a light entering from the light entrance end surface goes            out as guided in a predetermined direction;        -   an opposite surface, provided on the other plate surface            opposite to the light exit surface; and        -   a plurality of circular-arcing slanted surfaces, provided on            either the opposite surface or the light exit surface, and            forming circular-arcs concentric with a semicircle having            its center at substantially a center of a length of an edge            of the light entrance end surface intersecting with the            light exit surface, for emitting, from the light exit            surface, lights entering from at least two positions on the            light entrance end surface, which positions are apart from            the center of the light entrance end surface by a            predetermined distance on both sides of the center, by            changing advancing directions of the lights to directions            inclined with respect to a vertical reference plane at            respective angles corresponding to the distance from the            center, of the positions from which the lights have entered,            and parallel with respective planes perpendicular to a            horizontal reference plane, where the vertical reference            plane is a plane perpendicular to both the light exit            surface and the light entrance end surface, and the            horizontal reference plane is a plane including a normal            line of the light exit surface and perpendicular to the            vertical reference plane, and    -   (ii) first and second light emitting elements, disposed on the        light entrance end surface of the light guide plate at positions        on both sides of a center, which is a center of a longer        dimension of the light entrance end surface at which a center of        curvature of arcs of the circular-arcing slanted surfaces is        defined, so as to face each other at the positions apart from        the center by a substantially same distance, for entering        illumination lights into the light guide plate from the light        entrance end surface, and

(3) a control device comprising a display drive circuit for sequentiallydisplaying two different images on the display panel, and a light sourcedrive circuit for controlling lighting of the first and second lightemitting elements in accordance with the images displayed on the displaypanel.

According to the display apparatus according to the second aspect,different images can be displayed toward the right hand side and lefthand side of the front-forward direction of the display apparatus. Whenthe present display apparatus is applied to a three-dimensional displayapparatus, it is possible to display a bright three-dimensional image byusing illumination lights to be emitted toward the left and right handsides as a left eye illumination light and a right eye illuminationlight to be recognized by the left and right eyes respectively. Further,by adjusting the positions of the two light sources disposed on thelight entrance end surface of the light guide plate to enlarge theangles of the lights emitted toward the left and right hand sides, it ispossible to make the image viewable from the right hand side and theimage viewable from the left hand side different from each other, andthereby to display completely different images toward the right handside and the left hand side.

In the present display apparatus, it is preferred that thecircular-arcing slanted surfaces be constituted by a plurality ofcircular-arcing reflection surfaces formed on the opposite surface ofthe light guide plate, to have shapes of semicircular arcs formedplurally on concentric circles centered at the center of the longerdimension of the light entrance end surface, for reflecting a firstlight emitted from the first light emitting element disposed on thelight entrance end surface to travel inside the light guide plate, sothat the first light will be emitted from the light exit surface withits advancing direction changed to a first direction inclined at apredetermined angle with respect to the vertical reference plane towardone side of the vertical reference plane on the horizontal referenceplane, and for reflecting a second light emitted from the second lightemitting element disposed on the light entrance end surface to travelinside the light guide plate, so that the second light will be emittedfrom the light exit surface with its advancing direction changed to asecond direction inclined at a predetermined angle with respect to thevertical reference plane toward the other side of the vertical referenceplane on the horizontal reference plane.

Alternatively, it is preferred that the display apparatus furthercomprise a prism sheet disposed outside the light exit surface of thelight guide plate, and having a plurality of circular-arcing prismsformed to have shapes of semicircular arcs formed plurally on concentriccircles centered at a point corresponding to the center of curvature ofthe circular-arcing slanted surfaces of the light guide plate, forrefracting a light emitted from the light guide plate in a directionparallel with the horizontal reference plane, and

the circular-arcing slanted surfaces be constituted by a plurality ofcircular-arcing refraction surfaces formed on the light exit surface ofthe light guide plate, to have shapes of semicircular arcs formedplurally on concentric circles centered at the center of the longerdimension of the light entrance end surface, for refracting, togetherwith the prism sheet, a first light emitted from the first lightemitting element disposed on the light entrance end surface to travelinside the light guide plate, so that the first light will be emittedfrom the light exit surface with its advancing direction changed to afirst direction inclined at a predetermined angle with respect to thevertical reference plane toward one side of the vertical reference planeand parallel with a plane perpendicular to the horizontal referenceplane, and for refracting, together with the prism sheet, a second lightemitted from the second light emitting element disposed on the lightentrance end surface to travel inside the light guide plate, so that thesecond light will be emitted from the light exit surface with itsadvancing direction changed to a second direction inclined at apredetermined angle with respect to the vertical reference plane towardthe other side of the vertical reference plane and parallel with a planeperpendicular to the horizontal reference plane.

It is further preferred that the display apparatus further comprise athird light emitting element, disposed correspondingly to the center ofthe light entrance end surface of the light guide plate at which thecenter of curvature of arcs of the circular-arcing slanted surfaces isdefined, for entering an illumination light into the light guide platefrom the center of the light entrance end surface, the light sourcedrive circuit comprise a lighting control circuit for selectingalternate lighting of the first and second light emitting elements, andsimultaneous lighting of the first, second, and third light emittingelements, and the light guide plate have a plurality of circular-arcingslanted surfaces for emitting a light entering from the center of thelight entrance end surface from the light exit surface, by changing anadvancing direction of the light to a direction parallel with thevertical reference plane. According to this structure, bright displaycan be achieved in the front-forward direction of the display apparatus.

It is further preferred that the display apparatus further comprise ananisotropic dispersion plate, disposed outside the light exit surface ofthe light guide plate so as to face the light exit surface, fordispersing a light emitted from the light exit surface, in directionsinclined at predetermined angles within a predetermined range of angles,with respect to the vertical reference plane on the horizontal referenceplane, or comprise fourth and fifth light emitting elements, disposed onthe light entrance end surface of the light guide plate, on externalsides of the first and second light emitting elements respectively, soas to face each other at positions at substantially an equal distancefrom the center at which the center of curvature of the arcs of thecircular-arcing slanted surfaces is defined, for entering illuminationlights into the light guide plate from the light entrance end surface,and the light source drive circuit comprise a lighting control circuitfor alternately performing simultaneous lighting of the first and fourthlight emitting elements disposed on one side of the center, andsimultaneous lighting of the second and fifth light emitting elementsdisposed on the other side of the center. According to this structure,the range of angles of view is broadened in the range of directionsinclined from the display apparatus.

A display apparatus according to a third aspect of the present inventioncomprises

(1) a display panel having a display area on which a plurality of pixelsare arranged in a matrix, for displaying at least one image by theplurality of pixels when a display signal corresponding to image datafor displaying an image is supplied to each of the plurality of pixels,

(2) an illuminator comprising

-   -   (i) a light guide plate having:        -   a light entrance end surface, provided on one end surface of            a plate-like transparent material, from which a light from a            light source enters;        -   a light exit surface, provided on a plate surface            intersecting with the light entrance end surface, from which            a light entering from the light entrance end surface goes            out as guided in a predetermined direction;        -   an opposite surface, provided on the other plate surface            opposite to the light exit surface; and        -   a plurality of circular-arcing slanted surfaces, provided on            either the opposite surface or the light exit surface, and            forming circular-arcs concentric with a semicircle having            its center at substantially a center of a length of an edge            of the light entrance end surface intersecting with the            light exit surface, for emitting, from the light exit            surface, lights entering from at least two positions on the            light entrance end surface, which positions are apart from            the center of the light entrance end surface by a            predetermined distance on both sides of the center, by            changing advancing directions of the lights to directions            inclined with respect to a vertical reference plane at            respective angles corresponding to the distance from the            center, of the positions from which the lights have entered,            and parallel with respective planes perpendicular to a            horizontal reference plane, where the vertical reference            plane is a plane perpendicular to both the light exit            surface and the light entrance end surface, and the            horizontal reference plane is a plane including a normal            line of the light exit surface and perpendicular to the            vertical reference plane, and    -   (ii) first and second light emitting elements, disposed on the        light entrance end surface of the light guide plate at positions        on both sides of a center, which is a center of a longer        dimension of the light entrance end surface at which a center of        curvature of arcs of the circular-arcing slanted surfaces is        defined, so as to face each other at the positions apart from        the center by a substantially same distance, for entering        illumination lights into the light guide plate from the light        entrance end surface,

(3) a display drive circuit for alternately displaying two images havinga parallax corresponding to images recognized by left and right eyes ofa viewer, on the display panel, and

(4) a light source drive circuit for alternately lighting the first andsecond light emitting elements in accordance with display of the twoimages,

wherein the illuminator is disposed at a back of the display panel, suchthat the vertical reference plane is disposed in line with an up anddown orientation of the display panel.

According to the display apparatus according to the third aspect,three-dimensional display is achieved by an illuminator having a simplestructure.

In this case, it is preferred that the circular-arcing slanted surfacesare constituted by a plurality of circular-arcing reflection surfacesformed on the opposite surface of the light guide plate, to have shapesof semicircular arcs formed plurally on concentric circles centered atthe center of the longer dimension of the light entrance end surface,for reflecting a first light emitted from the first light emittingelement disposed on the light entrance end surface to travel inside thelight guide plate, so that the first light will be emitted toward thedisplay panel as changed into a left eye illumination light having adirectivity which will make an emission light intensity peak appear in afirst direction inclined with respect to a normal line of the displaypanel toward one eye of the left and right eyes of the viewer, and forreflecting a second light emitted from the second light emitting elementdisposed on the light entrance end surface to travel inside the lightguide plate, so that the second light will be emitted toward the displaypanel as changed into a right eye illumination light having adirectivity which will make an emission light intensity peak appear in asecond direction inclined toward the other eye.

Alternatively, it is preferred that the display apparatus furthercomprise a prism sheet disposed outside the light exit surface of thelight guide plate, for refracting a light emitted from the light guideplate in a direction parallel with the horizontal reference plane, andthe circular-arcing slanted surfaces be constituted by a plurality ofcircular-arcing refraction surfaces formed on the light exit surface ofthe light guide plate, to have shapes of semicircular arcs formedplurally on concentric circles centered at the center of the longerdimension of the light entrance end surface, for refracting, togetherwith the prism sheet, a first light emitted from the first lightemitting element disposed on the light entrance end surface of the lightguide plate to travel inside the light guide plate, so that the firstlight will be emitted toward the display panel as changed into a lefteye illumination light having a directivity which will make an emissionlight intensity peak appear in a first direction inclined with respectto a normal line of the display panel toward one eye of the left andright eyes of the viewer, and for refracting, together with the prismsheet, a second light emitted from the second light emitting elementdisposed on the light entrance end surface to travel inside the lightguide plate, so that the second light will be emitted toward the displaypanel as changed into a right eye illumination light having adirectivity which will make an emission light intensity peak appear in asecond direction inclined toward the other eye.

It is further preferred that the display apparatus further comprise athird light emitting element, disposed correspondingly to the center ofthe light entrance end surface of the light guide plate at which thecenter of curvature of arcs of the circular-arcing slanted surfaces isdefined, for entering an illumination light into the light guide platefrom the center of the light entrance end surface, the light guide platehave a plurality of circular-arcing slanted surfaces for emitting alight entering from the center of the light entrance end surface fromthe light exit surface, by changing an advancing direction of the lightso that the light will have an emission light intensity peak in adirection substantially parallel with a normal line of the light exitsurface, and the light source drive circuit comprise a lighting controlcircuit for selecting alternate lighting of the first and second lightemitting elements, and simultaneous lighting of the first, second, andthird light emitting elements. According to this structure, a brighttwo-dimensional image can be displayed in the front-forward direction ofthe display apparatus.

It is further preferred that the display apparatus further comprisefourth and fifth light emitting elements, disposed on the light entranceend surface of the light guide plate, on external sides of the first andsecond light emitting elements respectively, so as to face each other atpositions at substantially an equal distance from the center at whichthe center of curvature of the arcs of the circular-arcing slantedsurfaces is defined, for entering illumination lights into the lightguide plate from the light entrance end surface, and the light sourcedrive circuit comprise a lighting control circuit for alternatelyperforming simultaneous lighting of the first and fourth light emittingelements disposed on one side of the center, and simultaneous lightingof the second and fifth light emitting elements disposed on the otherside of the center. According to this structure, three-dimensionaldisplay is available in the front-forward direction of the displayapparatus, and a two-dimensional image for the left or right eye imagecan be recognized from inclined directions in a broad range.

BRIEF DESCRIPTION OF THE DRAWINGS

These objects and other objects and advantages of the present inventionwill become more apparent upon reading of the following detaileddescription and the accompanying drawings in which:

FIG. 1 is an exploded perspective view of a display apparatus showingthe first embodiment of the present invention;

FIG. 2 is a cross-sectional view of a portion of a liquid crystaldisplay panel used in the display apparatus shown in FIG. 1;

FIG. 3 is a front elevation of an illuminator used in the displayapparatus shown in FIG. 1, as seen from in front of its light exit side;

FIG. 4 is a perspective view showing how a light entering into a lightguide plate travels, in the illuminator shown in FIG. 3;

FIG. 5 is a cross-sectional view of the illuminator shown in FIG. 3;

FIG. 6 is a plan view of the illuminator shown in FIG. 3, as seen fromin front of its light entrance surface on which light emitting elementsare disposed;

FIG. 7 is a distribution graph of the light intensity of light emittedfrom the illuminator according to the first embodiment;

FIG. 8 is a front elevation of an illuminator showing the secondembodiment of the present invention, as seen from in front of its lightexit surface;

FIG. 9 is a cross-sectional view of the illuminator shown in FIG. 8;

FIG. 10 is a front elevation of an illuminator showing the thirdembodiment of the present invention, as seen from in front of its lightexit surface;

FIG. 11 is a distribution graph of the light intensity of light emittedfrom the illuminator according to the third embodiment shown in FIG. 10;

FIG. 12 is an exploded perspective view of a display apparatus showingthe fourth embodiment of the present invention;

FIG. 13 is a plan view of an illuminator shown in FIG. 12, as seen fromin front of its light entrance surface on which light emitting elementsare disposed;

FIG. 14 is a distribution graph of the light intensity of light emittedfrom the illuminator of the fourth embodiment shown in FIG. 13;

FIG. 15 is an exploded perspective view of a display apparatus showingthe fifth embodiment of the present invention;

FIG. 16 is a plan view of an illuminator shown in FIG. 15, as seen fromin front of its light entrance surface on which light emitting elementsare disposed;

FIG. 17 is a front elevation of the illuminator used in the displayapparatus shown in FIG. 15, as seen from in front of its light exitsurface;

FIG. 18 is a distribution graph of the light intensity of light emittedfrom the illuminator of the fifth embodiment shown in FIG. 15;

FIG. 19 is an exploded perspective view of a display apparatus showingthe sixth embodiment of the present invention; and

FIG. 20 is a distribution graph of the light intensity of light emittedfrom the illuminator of the sixth embodiment shown in FIG. 19.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

FIG. 1 to FIG. 7 show the first embodiment of the present invention. Anexample where an illuminator according to the present invention isapplied to a display apparatus for performing three-dimensional display,will be explained.

As shown in FIG. 1, the present display apparatus comprises a displayarea 1 a on which a plurality of pixels (unillustrated) are arranged ina matrix, a liquid crystal display panel 1 on which at least one imageis displayed by the plurality of pixels each supplied with a displaysignal corresponding to image data for displaying an image, anilluminator 15 disposed behind the back surface of the liquid crystaldisplay panel 1 counter to the observation side, and a control device 32for controlling the display by the liquid crystal display panel 1.

FIG. 2 is a cross-sectional view of one portion of the liquid crystaldisplay panel 1. The liquid crystal display panel 1 comprises a pair oftransparent substrates 2 and 3 jointed to each other via a frame-likesealing member 4 (see FIG. 1), transparent electrodes 5 and 6 formed onthe opposite internal surfaces of the substrates 2 and 3 respectively,to define a plurality of pixels arranged in a matrix in the area wherethe electrodes 5 and 6 face each other, and a nematic liquid crystallayer 9 provided in the area enclosed by the sealing member 4 betweenthe pair of substrates 2 and 3.

The liquid crystal display panel 1 used in the present embodiment is anactive matrix liquid crystal display panel, in which a plurality ofpixel electrodes 5 are formed on the internal surface of one of the pairof substrates 2 and 3, for example, on the internal surface of thesubstrate 2 counter to the observation side (the lower side in FIG. 2)in a matrix of row direction (left and right orientation in FIG. 2) andcolumn direction (front and back orientation in FIG. 2), and amonolithic-frame-like opposite electrode 6 facing the plurality of pixelelectrodes 5 is formed on the internal surface of the other substrate 3on the observation side. The opposite substrate 2 is provided, on itsinternal surface, with a plurality of TFTs (Thin Film Transistors)connected to the plurality of pixel electrodes 5 respectively, aplurality of gate lines each supplying a gate signal to the TFTs on thecorresponding row, and a plurality of data lines each supplying an imagedata signal to the TFTs on the corresponding column, although omittedfrom FIG. 2.

The present liquid crystal display panel 1 is a liquid crystal displaypanel of a bent orientation type having a quick responsibility, or of ahomogeneous alignment type having no twist in the alignment of liquidcrystal molecules and imparted with a quick responsibility by reducingthe liquid crystal layer thickness (gap between the substrates). In caseof a bent orientation liquid crystal display panel, the liquid crystalmolecules 9 a in the liquid crystal layer 9 are brought into sprayalignment, with their pretilt angle controlled by homogeneous aligningfilms 7 and 8 formed so as to cover the electrodes 5 and 6 on theinternal surfaces of the pair of substrates 2 and 3. In case of ahomogeneous alignment liquid crystal display panel, the liquid crystalmolecules 9 a in the liquid crystal layer 9 are brought into homogeneousalignment, with their aligning direction defined by the homogeneousaligning films 7 and 8 such that the longer axis of the molecules is setin a uniform direction.

A pair of polarizing plates 10 and 11 are disposed on the externalsurfaces of the pair of substrates 2 and 3, with their transmission axisarranged in a predetermined direction. A retardation plate 12 forimproving display contrast is disposed between one of the pair ofsubstrates 2 and 3, for example, the substrate 3 on the observation sideand the polarizing plate 11 on the observation side.

The substrate 2 opposite to the observation side of the liquid crystaldisplay panel 1 is provided, as shown in FIG. 1, with driver mountingportions 2 a and 2 b which are drawn out to the outside of theobservation side substrate 3, at one edge in the row direction and atone edge in the column direction. The aforementioned plurality of gatelines are connected to a gate driver 13 mounted on the driver mountingportion 2 a in the row direction, and the plurality of data lines areconnected to a data driver 14 mounted on the driver mounting portion 2 bin the column direction. The opposite electrode 6 is connected to asupply source for supplying an opposite electrode potential, whichsource is included in one or both of the gate driver 13 and data driver14, through unillstrated cross couplers provided at the portions wherethe substrates area jointed by the sealing member 4 and through anunillustrated opposite electrode connection line formed on one or bothof the driver mounting portions 2 a and 2 b.

The illuminator 15 disposed at a side opposite to the observation sideof the liquid crystal display panel 1 will now be explained. FIG. 3 is afront elevation of the illuminator 15, seen from in front of its lightexit. FIG. 4 is a perspective view showing how a light coming into alight guide plate travels in the illuminator 15 shown in FIG. 3. FIG. 5is a cross-sectional view showing the cross-sectional structure of theilluminator 15, with no hatching. FIG. 6 is a plan view of theilluminator 15, seen from in front of its light entrance where lightemitting elements are disposed.

The illuminator 15 comprises a light direction changing member 16, afirst light emitting element 30 a, and a second light emitting element30 b. The light direction changing member 16 has its light entrance endsurface 18, from which a light enters, formed along either one of theupper and lower edges of the screen surface of the liquid crystaldisplay panel 1, substantially in parallel with the left and rightorientation of the liquid crystal display panel 1. The light directionchanging member 16 has, on either its surface facing the liquid crystaldisplay panel 1 or its opposite surface opposite thereto, a plurality ofconcentric circular-arcing slanted surfaces 20, which form circular arcsconcentric with a semicircle having its center 18 a at the mid point ofthe longer dimension of the light entrance end surface 18, for emittingthe light coming from the light entrance end surface 18 toward theliquid crystal display panel 1 by changing the direction of the light.The first and second light emitting elements 30 a and 30 b are disposednear the center 18 a of the light entrance end surface 18 of the lightdirection changing member 16, at positions P1 and P2 at substantially anequal distance 40 leftward and rightward from the center of curvature ofthe circular-arcing slanted surfaces 20, for emitting lights dispersingleftward and rightward toward the light entrance end surface 18.

The light direction changing member 16 of the illuminator 15 isconstituted by a light guide plate 17 made of plate-like transparentmaterial such as acrylic resin plate. Among the surrounding four endsurfaces of the light guide plate 17, one end surface corresponding toone of the upper and lower edges of the screen surface of the liquidcrystal display panel 1, for example, corresponding to the upper edge ofthe screen surface, serves as the light entrance end surface 18 fromwhich a light enters. One of the plate surfaces of the transparent plateconstructing the light guide plate 17, that faces the liquid crystaldisplay panel 1, which is a planar surface substantially parallel withthe substrates 2 and 3 of the liquid crystal display panel 1, serves asa light exit surface 19 from which a light is externally emitted. Thecircular-arcing slanted surfaces 20 are formed on the surface counter(opposite) to the light exit surface 19 of the light guide plate 17. Thecircular-arcing slanted surfaces 20 are formed in a plural number inshapes of circular arcs concentric with the semicircle having its center18 a at the mid point of the longer dimension of the light entrance endsurface 18. The circular-arcing slanted surfaces 20 change the directionof the light coming into the transparent plate from the light entranceend surface 18, and emit the light from the light exit surface 19 towardthe liquid crystal display panel 1.

Although exaggerated and shown large in the drawing, the circular-arcingslanted surfaces 20 of the light guide plate 17 are formedconcentrically at a pitch almost equal to or smaller than the pixel pithof the liquid crystal display panel 1.

Each of the plurality of circular-arcing slanted surfaces 20 of thelight guide plate 17 is a slanted surface oriented toward the center ofthe semicircle, and inclined at a predetermined angle in a directionopposite to the light exit surface 19.

As indicated by the arrows in FIG. 3 to FIG. 6, the light guide plate 17changes the direction of a light coming from the light entrance endsurface 18 by totally reflecting the light on the interface between theplurality of circular-arcing slanted surfaces 20 and the atmosphere(air), and emits the light from the light exit surface 19 toward theliquid crystal display panel 1 by reflecting the light on the interfacebetween the light exit surface 19 and the atmosphere in a direction inwhich the light will be at a smaller angle with respect to the normalline of the light exit surface 19. The angle of inclination of theplurality of circular-arcing slanted surfaces 20 is set such that, whena light that will disperse leftward and rightward is entered from thecenter of curvature of the circular-arcing slanted surfaces 20, a lighthaving such a directivity as will make the emission light intensity peakappear in a direction parallel with the normal line of the liquidcrystal display panel 1, will be emitted from the light exit surface 19of the light guide plate 17.

That is, on the light guide plate 17 constituting the light directionchanging member 16, the circular-arcing slanted surfaces 20 are formedso as to arc along the semicircle centered at the center 18 a which issubstantially the mid point of the length of an edge of the lightentrance end surface 18 intersecting with the light exit surface 19, andso as to internally reflect a light entering from the center 18 a of thelight entrance end surface 18 such that the light will be emitted in thedirection of the normal line of the light exit surface 19 of the lightguide plate 17. Assuming that a plane perpendicular to both the lightexit surface 19 and the light entrance end surface 18 is a verticalreference plane 16 v and a plane including the normal line of the lightexit surface 19 and perpendicular to the vertical reference plane 16 vis a horizontal reference plane 16 h, the light direction changingmember 16 emits lights entering from the positions of the first andsecond light emitting elements 30 a and 30 b by changing the advancingdirections of the lights to directions inclined from the verticalreference plane 16 v at respective angles corresponding to the distancefrom the center, of the positions from which the lights have entered,and parallel with respective -planes perpendicular to the horizontalreference plane 16 h as indicated by the two-dot chain lines in FIG. 4.The first light emitting element 30 a and the second light emittingelement 30 b are disposed at positions which are apart from the center18 a of the light entrance end surface 18 by a predetermined distancetoward both sides of the center 18 a.

To be more specific, the light direction changing member 16 is provided,on the surface of the light guide plate 17 opposite to the light exitsurface 19, with the plurality of circular-arcing slanted surfaces 20,which are formed plurally on concentric circles centered at the center18 a of the longer dimension of the light entrance end surface 18. Theadvancing direction of a first light, emitted from the first lightemitting element 30 a disposed on the light entrance end surface 18 totravel inside the light guide plate 17, is changed by thecircular-arcing slanted surfaces 20, to a first direction inclined at apredetermined angle from the vertical reference plane 16 v toward oneside of the vertical reference plane 16 v on the horizontal referenceplane 16 h, and the first light is emitted in this direction. A secondlight, emitted from the second light emitting element 30 b disposed onthe light entrance end surface 18 to travel inside the light guide plate17, is emitted from the light exit surface 19, with its advancingdirection changed to a second direction inclined at a predeterminedangle from the vertical reference plane 16 v toward the opposite sidethereof on the horizontal reference plane 16 h.

According to the present embodiment, a reflection plate 21 forreflecting a light that passes through the interface between thecircular-arcing slanted surfaces 20 and the atmosphere to escape to theback of the light guide plate 17 (to the outside of the surface on whichthe circular-arcing slanted surfaces 20 are formed), among the lightscoming into the light guide plate 17 from the light entrance end surface18 a, is disposed at the back of the light guide plate 17.

The structure of the first and second light emitting diodes 30 a and 30b is not illustrated, but they each comprise an LED (Light EmittingDiode) molded with transparent resin, and have, at their light emissionside, a lens for radiating the light emitted from the light emittingpoint of their LED by spreading (dispersing) the light over a planeparallel with the light exit surface 19 of the light guide plate 17.

The first and second light emitting elements 30 a and 30 b are disposedat the left and right sides of the center of curvature of thecircular-arcing slanted surfaces 20 a at the mid point of the lightentrance end surface 18 a of the light guide plate 17, so as to be apartfrom the center 18 a by a substantially same distance 40, and such thatthe directions of dispersion of the lights emitted from the lightemitting elements 30 a and 30 b are in line with the orientation of thelonger dimension of the light entrance end surface 18 of the light guideplate 17, i.e., in line with the left and right orientation of thescreen surface of the liquid crystal display panel 1.

The illuminator 15 lets out a light, emitted from the light emittingelement 30 a, of the first and second light emitting elements 30 a and30 b, that is on the right side as seen from the observation side of theliquid crystal display panel 1, as a left eye illumination light havinga directivity which will make the emission light intensity peak appearin a direction inclined from the normal line of the liquid crystaldisplay panel 1 toward the left eye of the viewer, by changing thedirection of the light by the plurality of circular-arcing slantedsurfaces 20 of the light guide plate 17 as indicated by the arrows inFIG. 3 to FIG. 6. The illuminator 15 lets out a light, emitted from thelight emitting element 30 b on the left side as seen from theobservation side, as a right eye illumination light having a directivitywhich will make the emission light intensity peak appear in a directioninclined from the normal line of the liquid crystal display panel 1toward the right eye of the viewer, by changing the direction of thelight by the plurality of circular-arcing slanted surfaces 20 of thelight guide plate 17 as indicated by the broken arrows in FIG. 3 to FIG.6.

That is, the first and second light emitting elements 30 a and 30 b aredisposed near the center 18 a of the light entrance end surface 18 ofthe light guide plate 17 to have substantially the same distance 40 fromthe center of curvature of the circular-arcing slanted surfaces 20leftward and rightward respectively. As a result, a light, emitted fromthe light emitting element 30 a, of the first and second light emittingelements 30 a and 30 b, that is on the right side as seen from theobservation side of the liquid crystal display panel 1, is reflected bythe plurality of circular-arcing slanted surfaces 20 in a direction 30 a1, which is inclined by an angle θ toward the left side as seen from theobservation side from a direction 30 n in which a light from the center18 a of curvature of the circular-arcing slanted surfaces 20 a isreflected. A light, emitted from the light emitting element 30 b on theleft side as seen from the observation side, is reflected by theplurality of circular-arcing slanted surfaces 20 in a direction 30 b 1which is inclined toward the right side as seen from the observationside from the direction 30 n in which the light from the center 18 a ofcurvature of the circular-arcing slanted surfaces 20 is reflected.

As described above, the angle of inclination of the plurality ofcircular-arcing slanted surfaces 20 of the light guide plate 17 is setsuch that, when a light dispersing leftward and rightward from thecenter of curvature of the circular-arcing slanted surfaces 20 isentered into the light guide plate 17, a light having a directivitywhich will make the emission light intensity peak appear in a directionparallel with the normal line of the liquid crystal display panel 1 willbe emitted from the light exit surface 19 of the light guide plate 17.Accordingly, when the light emitting element 30 a on the right side asseen from the observation side is lit, i.e., when a light dispersingleftward and rightward from the point deviated to the right side fromthe center of curvature of the circular-arcing slanted surfaces 20 isentered into the light guide plate 17, a left eye illumination lighthaving a directivity which will make the emission light intensity peakappear in a direction inclined from the normal line of the liquidcrystal display panel 1 toward the left side as seen from theobservation side of the liquid crystal display panel, i.e., inclinedtoward the direction of the left eye of the viewer, will be emitted fromthe light exit surface 19 of the light guide plate 17. When thesolid-state light emitting element 30 b on the left side as seen fromthe observation side is lit, i.e., when a light dispersing leftward andrightward from the point deviated to the left side from the center ofcurvature of the circular-arcing slanted surfaces 20 is entered into thelight guide plate 17, a right eye illumination light having adirectivity which will make the emission light intensity peak appear ina direction inclined to the right side as seen from the observation sideof the liquid crystal display panel 1, i.e., inclined to the right eyeof the viewer, will be emitted.

FIG. 7 shows the distribution of the light intensity of the left eyeillumination light and right eye illumination light emitted from theilluminator 15. In FIG. 7, the negative angles indicate the angles inthe left side as seen from observation side of the illuminator 15 withrespect to the normal line (vertical reference plane 16 v) of theilluminator 15. The positive angles indicate the angles in the rightside as seen from the observation side with respect to the normal lineof the illuminator 15. As shown in FIG. 7, emission lights having strongdirectivities which will make the light intensity peaks appear in therange of angles of 7° to 8° in both the left and right sides of thenormal line of the illuminator 15 is achieved.

The control device 32 shown in FIG. 1 comprises a display drive circuit32 a for controlling the gate driver 13 and the data driver 14, a lightsource drive circuit 32 b for controlling the lighting of the first andsecond light emitting elements 30 a and 30 b of the illuminator 15, anda control circuit 32 c for controlling the operations of the displaydrive circuit 32 a and light source drive circuit 32 b. The displaydrive circuit 32 a drives the liquid crystal display panel 1 so as tosequentially display two different images on the display panel 1. Incase of three-dimensional display, the display drive circuit 32 acontrols to alternately display two images, i.e., a right eye image anda left eye image, having a parallax corresponding to images to be viewedby the left and right eyes of the viewer. The light source drive circuit32 b alternately turns on the first and second light emitting elements30 a and 30 b, in synchronization with the display of the two images.

The display apparatus according to the first embodiment displays athree-dimensional color image by field sequential display, so the firstand second light emitting elements 30 a and 30 b each include a red LEDfor emitting a red light, a green LED for emitting a green light, and ablue LED for emitting a blue right, to selectively emit lights of threecolors of red, green, and blue.

The control device 32 selects, in an arbitrary order, left eye imagedata and right eye image data prepared for the respective three unitcolors of red, green, and blue, for respective six fields obtained byhexasecting one frame for displaying one three-dimensional color image,and sequentially supplies the selected image data to the pixels of theliquid crystal display panel 1. In synchronization with the display of aleft eye image for each of the respective unit colors of red, green, andblue, the control device 32 drives one LED for the color of the imagebeing displayed, among the LEDs for the three colors of red, green, andblue of the light emitting element 30 a on the right side so that a lefteye illumination light having that color will be emitted from theilluminator 15. In synchronization with the display of a right eye imagefor each of the respective unit colors of red, green, and blue, thecontrol device 32 turns on one LED for the color of the displayed image,among the LEDs for the three colors of red, green, and blue of the lightemitting element 30 b on the left side so that a right eye illuminationlight having that color will be emitted from the illuminator 15.

That is, according to the present display apparatus, the control device32 selectively supplies a signal for left eye image data for each of therespective unit colors of red, green, and blue, to the plurality ofpixels of the liquid crystal display panel 1 in order to display a lefteye image having each of the respective unit colors, and controls theilluminator 15 to emit a left eye illumination light having each of therespective unit colors of red, green, and blue in synchronization withthe display of the image for each color. The control device 32 suppliesa signal for right eye image data for each of the respective unit colorsto the pixels in order to display a right eye image for each of therespective unit colors, while controlling the illuminator 15 to emit aright eye illumination light having each of the respective unit colorsof red, green, and blue in synchronization with the display of the imagehaving each color. Therefore, left eye images for the respective unitcolors of red, green, and blue corresponding to the left eye image dataand right eye images for the respective unit colors of red, green, andblue corresponding to the right eye image data are sequentiallydisplayed on the liquid crystal display panel 1, so that the viewer willview a three-dimensional image.

Since the present display apparatus sequentially performs displaying ofleft eye images using all the pixels on the liquid crystal display panel1 and displaying of right eye images using all the pixels on the liquidcrystal display panel 1, a three-dimensional image having a high imagequality in which both the left eye images and the right eye images havea high resolution, can be displayed.

Further, since the present liquid crystal display apparatus has, behinditself, the illuminator, which emits lights having directivities indirections toward both the left and right eyes, it can display athree-dimensional image having a favorable luminance balance between theleft eye images and the right eye images, in spite of its simplestructure.

As described above, in the illuminator 15, the light direction changingmember 16 is provided with the circular-arcing slanted surfaces 20,which form arcs along the semicircle having its center 18 a atsubstantially the mid point of the length of an edge of the lightentrance end surface 18 intersecting with the light exit surface 19, forinternally reflecting a light entering from the center 18 a of the lightentrance end surface 18 so as to be emitted in the direction of thenormal line of the light exit surface 19 of the light guide plate 17.Further, the first and second light emitting elements 30 a and 30 b aredisposed at positions on both sides of the center 18 a of the lightentrance end surface 18 of the light guide plate 17 apart from thecenter 18 a by a predetermined distance. Consequently, lights emittedfrom the respective light emitting elements can be emitted separately asa light whose advancing direction is changed to have a transmissionlight intensity peak in the left hand side with respect to the normalline of the illuminator 15, and as a light whose advancing direction ischanged to have a transmission light intensity peak in the right handside with respect to the normal line of the illuminator 15.

Furthermore, the present illuminator 15 has the circular-arcing slantedsurfaces 20 and the first and second light emitting elements 30 a and 30b. The circular-arcing slanted surfaces 20 are formed on one of theopposite surface and light exit surface 19 of the light guide plate 17and form arcs along the semicircle having its center 18 a atsubstantially the mid point of the length of an edge of the lightentrance end surface 18 intersecting with the light exit surface 19.Further, when assuming that a plane perpendicular to both the light exitsurface 19 and the light entrance end surface 18 is a vertical referenceplane 16 v and a plane including the normal line of the light exitsurface 19 and perpendicular to the vertical reference plane 16 v is ahorizontal reference plane 16 h, the circular-arcing slanted surfaces 20emit, from the light exit surface 19, lights entering from two positionson both sides of the center 18 a of the light entrance end surface 18apart from the center 18 a by a predetermined distance, by changing theadvancing directions of the respective lights, to the directions whichare inclined with respect to the vertical reference plane 16 v atrespective angles corresponding to the distance from the center, of thepositions from which the lights have entered, and parallel withrespective planes perpendicular to the horizontal reference plane 16 h.The first and second light emitting elements 30 a and 30 b are disposedat positions which are equidistantly apart from the center 18 a of thelonger dimension of the light entrance end surface 18 of the light guideplate 17, at which center 18 a the center of curvature of the arcs ofthe circular-arcing slanted surfaces 20 is defined, for enteringillumination lights into the light guide plate 17 from the lightentrance end surface 18. Accordingly, the illuminator 15 of the presentinvention can emit illumination lights having strong directivitiestoward the left and right sides as seen from the observation side of thelight exit surface 19.

When the present illuminator 15 is used as an illuminator forthree-dimensional display, a bright three-dimensional image can bedisplayed by using the illumination lights to be respectively emitted inthe left and right directions, as a left eye illumination light and aright eye illumination light to be recognized by the left and right eyesrespectively.

By adjusting the positions of the two light sources disposed on thelight entrance end surface 18 of the light guide plate 17 in order tomake the lights to be emitted toward the left and right directions havea larger angle, it is possible to make the image viewable from the lefthand side and the image viewable from the right hand side clearlydifferent from each other. Therefore, completely different images can bedisplayed toward the right hand side and the left hand side.

Second Embodiment

FIG. 8 and FIG. 9 show the second embodiment of the present invention.FIG. 8 is a front elevation of an illuminator, disposed so as to face asurface of the liquid crystal display panel 1 opposite to theobservation side, as seen from in front of the illuminator's light exitsurface. FIG. 9 is a cross sectional view of the illuminator.

The light direction changing member 16 of the second embodiment isdifferent from that of the first embodiment, but the other componentsare the same. Therefore, the same components will be denoted by the samereference numerals, and explanation for such components will be omitted.

An illuminator 115 according to the present embodiment comprises a lightguide plate 22, a prism sheet 27 disposed at the light exit side of thelight guide plate 22, and first and second light emitting elements 30 aand 30 b. The light guide plate 22 is made of plate-like transparentmaterial such as acrylic resin plate. Among the surrounding four endsurfaces of the light guide plate 22, one end surface corresponding toone of the upper and lower edges of the screen surface of the liquidcrystal display panel 1 serves as a light entrance end surface 23 fromwhich a light enters. The light guide plate 22 has, on one plate surfaceof the transparent plate, that faces the liquid crystal display panel 1,a plurality of concentric circular-arcing slanted surfaces 24, whichform circular arcs concentric with a semicircle having its center 23 aat the mid point of the longer dimension of the light entrance endsurface 23, for letting out a light coming from the light entrance endsurface 23 into the transparent plate, by changing the direction of thelight. The plate surface of the light guide plate 22, opposite to theplate surface on which the circular-arcing slanted surfaces 24 areformed, serves as a reflection surface 25 for reflecting a lightentering from the light entrance end surface 23 into the transparentplate, toward the circular-arcing slanted surfaces 24. The prism sheet27 has, on its surface facing the light guide plate 22, a plurality ofconcentric circular-arcing prisms 28, which form circular arcsconcentric with a semicircle having its center at a positioncorresponding to the center 23 a of curvature of the circular-arcingslanted surfaces 24 of the light guide plate 22, for refracting a lightemitted from the light guide plate 22 toward a direction in which thelight will be at a smaller angle with respect to the normal line of theliquid crystal display panel 1. The surface of the prism sheet 27 facingthe liquid crystal display panel 1, which is a planar surfacesubstantially parallel with the substrates 2 and 3 of the liquid crystaldisplay panel 1, serves as a light exit surface 29 from which a lightrefracted by the plurality of circular-arcing prisms 28 is emittedtoward the liquid crystal display panel 1. The light guide plate 22having the circular-arcing slanted surfaces 24, and the prism sheet 27constitute a light direction changing member 116. The first and secondlight emitting elements 30 a and 30 b are disposed near the center 23 aof the light entrance end surface 23 of the light guide plate 22 of thelight direction changing member 116, so as to face each other atpositions at substantially an equal distance 40 leftward and rightwardfrom the center 23 a of curvature of the circular-arcing slantedsurfaces 24, for emitting lights dispersedly leftward and rightward,toward the light entrance end surface 23 of the light guide plate 22.

Each of the plurality of circular-arcing slanted surfaces 24 of thelight guide plate 22 of the light direction changing member 116 is arefraction surface oriented toward the center 23 a of the semicircle,and inclined at a predetermined angle in a direction opposite to thereflection surface 25. Each of the plurality of circular-arcing prisms28 of the prism sheet 27 has a cross-sectional shape of an isoscelestriangle.

That is, the circular-arcing slanted surfaces 24 form circular-arcingrefraction surfaces, which form arcs concentric with the semicirclehaving its center at substantially the mid point of the length of anedge of the light entrance end surface 23 intersecting with the surfaceon which the circular-arcing slanted surfaces 24 is formed, forrefracting a light entering from the center 23 a of the light entranceend surface 23 so that the light will be emitted in a direction parallelwith the horizontal reference plane 16 h.

The plurality of circular-arcing slanted surfaces 24 emit, from thelight exit surface 29, a first light emitted from the first lightemitting element 30 a disposed on the light entrance end surface 23 totravel inside the light guide plate 22, by changing the advancingdirection of the first light to a first direction which is inclined, ata predetermined angle, from the vertical reference plane 16 v toward oneside, and parallel with a plane perpendicular to the horizontalreference plane 16 h. Further, the circular-arcing slanted surfaces 24refract a second light, emitted from the second light emitting element30 b disposed on the light entrance end surface 23 to travel inside thelight guide plate 22, so that the second light will be emitted from thelight exit surface 29 with its advancing direction changed to a seconddirection which is inclined, at a predetermined angle, from the verticalreference plane 16 v toward a side opposite to the one side, andparallel with a plane perpendicular to the horizontal reference plane 16h.

The prism sheet 27 comprises the plurality of circular-arcing prisms 28,which are shaped into semicircular arcs plurally concentrically disposedabout a point corresponding to the center 23 a of curvature of thecircular-arcing slanted surfaces 24 of the light guide plate 22, forrefracting a light emitted from the light guide plate 22 in a directionparallel with the horizontal reference plane 16 h.

According to the present embodiment, the reflection plate 25 of thelight guide plate 22 is formed by providing a reflection film 26 on theplate surface of the light guide plate 22. The reflection plate 25 ofthe light guide plate 22 may be a total reflection surface constitutedby the interface between the plate surface of the light guide plate 22and the atmosphere.

The present illuminator 115 emits a light, entering into the light guideplate 22 of the light direction changing member 116 from the lightentrance end surface 23, from the light guide plate 22, by changing thedirection of the light by the plurality of circular-arcing slantedsurfaces 24 as indicated by the arrows in FIG. 9, and refracts the lightby the plurality of circular-arcing prisms 28 on the prism sheet 27 soas to be emitted toward the liquid crystal display panel 1. The angle ofinclination of the plurality of circular-arcing slanted surfaces 24 ofthe light guide plate 22 and the angle of inclination of the twoinclined surfaces of each of the plurality of circular-arcing prisms 28of the prism sheet 27 are set such that, when a light dispersingleftward and rightward from the center 23 a of curvature of thecircular-arcing slanted surfaces 24 is entered into the light guideplate 22, a light having a directivity which will make the emissionlight intensity peak appear in a direction parallel with the normal lineof the liquid crystal display panel 1 will be emitted from the lightexit surface 29 of the prism sheet 27.

Hence, according to the illuminator 115, when the first light emittingelement 30 a disposed on the right side as seen from the observationside, of the first and second light emitting elements 30 a and 30 b, isturned on, i.e., when a light, dispersing leftward and rightward from apoint deviated to the right side from the center 23 a of curvature ofthe circular-arcing slanted surfaces 24, is entered into the light guideplate 22, a left eye illumination light having a directivity which willmake the emission light intensity peak appear in a direction inclined tothe left, as seen from the observation side of the liquid crystaldisplay panel 1, from the normal line of the liquid crystal displaypanel 1, i.e., inclined toward the left eye of the viewer, will beemitted from the light exit surface 29 of the prism sheet 27, asindicated by arrows in FIG. 8. When the second light emitting element 30b disposed on the left side as seen from the observation side is turnedon, i.e., when a light, dispersing leftward and rightward from a pointdeviated to the left side from the center 23 a of curvature of thecircular-arcing slanted surfaces 24 is entered into the light guideplate 22, a right eye illumination light having a directivity which willmake the emission light intensity peak appear in a direction inclined tothe right, as seen from the observation side of the liquid crystaldisplay panel 1, from the normal line of the liquid crystal displaypanel 1, i.e., inclined toward the right eye of the viewer, will beemitted from the light exit surface 29 of the prism sheet 27, asindicated by broken arrows in FIG. 8.

Thus, the illuminator 115 according to the present embodiment can emit aleft eye illumination light by turning on the light emitting element 30a on the right side as seen from the observation side of the liquidcrystal display panel 1, of the first and second light emitting elements30 a and 30 b, and can emit a right eye illumination light by turning onthe light emitting element 30 b on the left side as seen from theobservation side.

Third Embodiment

FIG. 10 and FIG. 11 show the third embodiment of the present invention.FIG. 10 is a front elevation of an illuminator, disposed so as to face asurface of the liquid crystal display panel 1 opposite to theobservation side, as seen from in front of the illuminator's light exitsurface. FIG. 11 is a distribution graph of the light intensity of lightemitted from the illuminator according to the third embodiment.According to the third embodiment, a third light emitting element isadditionally included in the structure of first embodiment, and theother components are the same as those of the first embodiment. Thus,the same components will be denoted by the same reference numerals, andexplanation for such components will be omitted.

According to the present embodiment, the illuminator 15 according to thefirst embodiment further comprises a third light emitting element 31,which is disposed between the first and second light emitting element 30a and 30 b so as to face the center of curvature of the circular-arcingslanted surfaces 20 of the light direction changing member 16, foremitting a light dispersing leftward and rightward toward the lightentrance end surface 18 of the light direction changing member 16.Further, the control device 32 comprises a display drive circuit 32 afor selectively displaying a two-dimensional image and athree-dimensional image on the plurality of pixels of the liquid crystaldisplay panel 1, and a light source drive circuit 32 b including alighting control circuit 32 b 1 for selectively performing alternatelighting of the first and second light emitting elements 30 a and 30 b,and simultaneous lighting of the first and second light emittingelements 30 a and 30 b and the third light emitting element 31, insynchronization with the display of the two-dimensional image and thethree-dimensional image.

The illuminator according to the present embodiment is equipped with thethird light emitting element 31, at a position corresponding to thecenter 18 a of the light entrance end surface 18 of the light guideplate 17 on which the center of curvature of the circular-arcing slantedsurfaces 20 is defined, for making a light enter into the light guideplate 17 from the center 18 a of the light entrance end surface 18.Further, the light guide plate 17 comprises the plurality ofcircular-arcing slanted surfaces 20 which cause a light, entering fromthe center 18 a of the light entrance end surface 18, to be emitted fromthe light exit surface 19, with its advancing direction changed to adirection parallel with the vertical reference plane 16 v. Accordingly,by the simultaneous lighting of the first and second light emittingelements 30 a and 30 b and the third light emitting element 31,illumination lights having directivities which will make the emissionlight intensity peaks appear in directions inclined to the left and theright, as seen from the observation side, from the normal line of theilluminator 15, are combined with a light having a directivity whichwill make the emission light intensity peak appear in a directionparallel with the normal line of the illuminator 15, thereby producingillumination light having a distribution of intensity as shown in FIG.11, making it possible to sufficiently raise the luminance in thefront-forward direction (normal line direction) of the illuminator 15.

Hence, the display apparatus according to the present embodimentdisplays left eye image data and right eye image data selectively on theplurality of pixels of the liquid crystal display panel 1, and displaysa steric three-dimensional image by lighting the first light emittingelement 30 a on the right side, as seen from the observation side of theliquid crystal display panel 1, of the first and second light emittingelements 30 a and 30 b of the illuminator 15, in synchronization withthe display of the left eye image, and by lighting the second lightemitting element 30 b on the left side, as seen from the observationside of the liquid crystal display panel 1, in synchronization with thedisplay of the right eye image. When the display apparatus displays atwo-dimensional image on the plurality of pixels of the liquid crystaldisplay panel 1, it can display the two-dimensional image brightly, bysimultaneously lighting the first and second light emitting elements 30a and 30 b and the third light emitting element 31 disposed between thetwo, in synchronization with the display of the two-dimensional image.

The present embodiment is achieved by adding the third light emittingelement 31 to the illuminator 15 of the first embodiment shown in FIG. 1to FIG. 7. However, the third light emitting element 31 may be added tothe illuminator 115 of the second embodiment shown in FIG. 8 and FIG. 9.

Furthermore, according to the first and second embodiments, the liquidcrystal display panel 1, which does not comprise a color filter, isemployed, to display a color image by field sequential display. However,the present invention can be applied to a liquid crystal displayapparatus, which displays a color image with the use of a liquid crystaldisplay panel comprising color filters having multiple colorscorresponding to the plurality of pixels, for example, color filtershaving three colors of red, green, and blue.

Fourth Embodiment

FIG. 12 to FIG. 14 show the fourth embodiment of the present invention.FIG. 12 is an exploded perspective view of a display apparatus. FIG. 13is a plan view of an illuminator according to the present embodiment, asseen from in front of its light entrance surface on which light emittingelements are disposed. FIG. 14 is a distribution graph of the lightintensity of light emitted from the illuminator according to the presentembodiment.

The fourth embodiment comprises, in addition to the components of thefirst embodiment, an anisotropic dispersion plate 50 having a functionfor dispersing a light in a specific range of angles, in order tobroaden the viewable range. The other components are the same. Thus, thesame components will be denoted by the same reference numerals, andexplanation for such components will be omitted.

According to the fourth embodiment, the anisotropic dispersion plate 50for allowing a light, entering thereinto at an angle of incidence withina predetermined range of angles with respect to the normal line of theplate surface thereof, to be dispersedly pass therethrough, is disposedbetween the liquid crystal display panel 1 and illuminator 15 of thedisplay apparatus shown in FIG. 1 to FIG. 7. The anisotropic dispersionplate 50 is disposed so as to face the light exit surface 19 of thelight guide plate 17 of the display apparatus. With a planeperpendicular to both the light exit surface 19 and the light entranceend surface 18 regarded as a vertical reference plane 16 v and a planeincluding the normal line of the light exit surface 19 and perpendicularto the vertical reference plane 16 v regarded as a horizontal referenceplane 16 h, the anisotropic dispersion plate 50 dispersedly emits eachlight, which enters thereinto at its own angle of incidence within apredetermined range of angles with respect to the vertical referenceplane 16 v on the horizontal reference plane 16 h.

The anisotropic dispersion plate 50 according to the present embodimenthas a dispersion characteristic of dispersing a light, which entersthereinto from a direction inclined, with respect to the verticalreference plane 16 v parallel with the up and down orientation of thedisplay apparatus, at an angle of 10° to 60° to both the left and theright on the horizontal reference plane 16 h. Accordingly, among thelights from the first and second light emitting elements 30 a and 30 bemitted from the light exit surface 19 of the light guide plate 17,lights emitted at angles within the range of 10° to 60° with respect tothe normal line of the anisotropic dispersion plate 50 to both the leftside and right side of the normal line, are dispersed by the anisotropicdispersion plate 50 to be entered into the liquid crystal display panel1, as shown in FIG. 13.

As a result, the present illuminator 15 can achieve illumination lighthaving a distribution of intensity in which a strong peak appears atangles of 7° to 8° with respect to the normal line of the light exitsurface 19 of the illuminator 15 in both the left side and the rightside, and intensities strong enough to make the displayed imagesviewable are achieved in the range of angles of 15° to 80°, as shown inFIG. 14.

Accordingly, by performing three-dimensional display in the same manneras the first embodiment by using the present illuminator 15, it ispossible to make a three-dimensional steric image be viewed from infront of the display apparatus by making a right eye image and a lefteye image be viewed by the respective eyes, while making the right eyeimage or the left eye image be viewed as a two-dimensional image fromthe right hand side position or the left hand side position which isgreatly inclined to the right side or the left side from the front ofthe display apparatus, making it possible to greatly broaden the rangeof view.

According to the present embodiment, the anisotropic dispersion plate 50is disposed between the illuminator 15 and liquid crystal display panel1 of the display apparatus according to the first embodiment. However,the present invention is not limited to this, but the anisotropicdispersion plate 50 may be disposed between the illuminator 115 andliquid crystal display panel 1 of the display apparatus according to thesecond embodiment. Also in this case, functions and effects similar tothose of the fourth embodiment can be achieved.

Further, the third embodiment may be applied to the fourth embodiment,to dispose the third light emitting element 31 correspondingly to thecenter 18 a of the light entrance end surface 18 of the light guideplate 17. In this case, a two-dimensional image having a high luminancein the front-forward direction and having a broad range of view can bedisplayed.

Fifth Embodiment

FIG. 15 to FIG. 18 show the fifth embodiment of the present invention.FIG. 15 is an exploded perspective view of a display apparatus. FIG. 16is a plan view of an illuminator according to the present embodiment, asseen from in front of its light entrance surface on which light emittingelements are disposed. FIG. 17 is a front elevation of the illuminatoraccording to the present embodiment, as seen from in front of its lightexit surface. FIG. 18 is a distribution graph of the light intensity oflight emitted from the illuminator according to the present embodiment.

The fifth embodiment aims for broadening the range of view, by addingfourth and fifth light emitting elements 30 c and 30 d to the structureof the first embodiment. The other components are the same as those ofthe first embodiment. Thus, the same components will be denoted by thesame reference numerals, and explanation for such components will beomitted.

The illuminator 215 according to the fifth embodiment is obtained byadditionally forming, on the light entrance end surface 18 of the lightguide plate of the illuminator 15 according to the first embodimentshown in FIG. 1 to FIG. 7, fourth and fifth light emitting elements 30 cand 30 d for entering illumination lighted into the light guide plate 17from the light entrance end surface 18. The fourth and fifth lightemitting elements 30 c and 30 d are disposed respectively on theexternal sides of the first and second light emitting elements 30 a and30 b which are disposed on the light entrance end surface 18, so as toface each other at positions at substantially an equal distance 41 fromthe center 18 a at which the center of curvature of the circular-arcingslanted surfaces 20 is defined. The light source drive circuit 32 bcomprises a circuit for controlling lighting of the first and secondlight emitting elements 30 a and 30 b and the fourth and fifth lightemitting elements 30 c and 30 d, i.e., a lighting control circuit 32 b 1for alternately performing simultaneous lighting of the first and fourthlight emitting elements 30 a and 30 c on one side of the center 18 a,and simultaneous lighting of the second and fifth light emittingelements 30 b and 30 d on the other side of the center 18 a.

Lights, emitted from the fourth and fifth light emitting elements 30 cand 30 d on the external sides of the first and second light emittingelements 30 a and 30 b disposed on the light entrance end surface 18 ofthe light guide plate 17, to enter into the light guide plate 17, havetheir advancing directions changed by the circular-arcing slantedsurfaces 20 to be emitted toward the liquid crystal display panel 1 aslights whose intensity peaks appear in directions which are moreinclined from the normal line, than such directions of lights from thefirst and second light emitting elements 30 a and 30 b, as shown in FIG.16 and FIG. 17, because the fourth and fifth light emitting elements 30c and 30 d are farther than the first and second light emitting element30 a and 30 b from the center 18 a.

That is, assuming that a plane perpendicular to both the light exitsurface 19 and the light entrance end surface 18 is a vertical referenceplan 16 v, and a plane including the normal line of the light exitsurface 19 and perpendicular to the vertical reference plane 16 v is ahorizontal reference plane 16 h, the lights emitted from the fourth andfifth light emitting elements 30 c and 30 d are emitted from theilluminator 215 as changed by the circular-arcing slanted surfaces 20into lights, whose intensity peaks appear in directions inclined, on thehorizontal reference plane 16 h, at an angle of 15° with respect to thevertical reference plane 16 v.

The illuminator 215 according to the present embodiment can achieveillumination light having a distribution of light intensity as shown inFIG. 18, having peaks of lights from the first and second light emittingelements 30 a and 30 b emitted from the light exit surface 19 of thelight guide plate 17, and peaks of lights from the fourth and fifthlight emitting elements 30 c and 30 d emitted from the light exitsurface 19 of the light guide plate.

Accordingly, by performing three-dimensional display in the same manneras the first embodiment by using the present illuminator 215, it ispossible to make a three-dimensional steric image be viewed from infront of the display apparatus by making a right eye image and a lefteye image be viewed by the respective eyes, while making the right eyeimage or the left eye image be viewed as a two-dimensional image fromthe right hand side position or the left hand side position which isinclined to the right side or the left side from the front of thedisplay apparatus at an angle of 15° to 20°, making it possible tobroaden the range of view.

In the present embodiment, an example has been shown, in which thefourth and fifth light emitting elements 30 c and 30 d are disposed onthe illuminator 15 of the display apparatus shown the first embodiment.However, the present invention is not limited to this, but the fifth andfourth light emitting elements 30 c and 30 d may be disposed on thelight guide plate 22 of the illuminator 115 of the display apparatusshown in the second embodiment. Also in this case, functions and effectssimilar to those of the present embodiment can be achieved.

The third embodiment may be applied to the present fifth embodiment todispose the third light emitting element 31 correspondingly to thecenter 18 a of the light entrance end surface 18 of the light guideplate 17. In this case, a two-dimensional image having a high luminancein the front-forward direction and having a broad range of view can bedisplayed.

Sixth Embodiment

FIG. 19 and FIG. 20 show the sixth embodiment of the present invention.FIG. 19 is an exploded perspective view of a display apparatus, and FIG.20 is a distribution graph of the light intensity of light emitted froman irradiator according to the present embodiment.

The sixth embodiment is for further broadening the range of view, byadding the fourth and fifth light emitting elements 30 c and 30 d shownin the fifth embodiment to the structure of the fourth embodiment. Theother components are the same as those of the fifth embodiment. Thus,the same components will be denoted by the same reference numerals, andexplanation for such components will be omitted.

The illuminator 215 according to the sixth embodiment is obtained byproviding the illuminator 15 of the display apparatus according to thefourth embodiment shown in FIG. 12 and FIG. 13, with the fourth andfifth light emitting elements 30 c and 30 d for entering illuminationlights into the light guide plate 17 from the light entrance end surface18. The fourth and fifth light emitting elements 30 c and 30 d aredisposed respectively on the external sides of the first and secondlight emitting elements 30 a and 30 b which are disposed on the lightentrance end surface 18 of the light guide plate of the illuminator 215,so as to face each other at positions at substantially an equal distance41 from the center 18 a at which the center of curvature of thecircular-arcing slanted surfaces 20 is defined. The light source drivecircuit 32 b comprises a circuit for controlling lighting of the firstand second light emitting elements 30 a and 30 b and the fourth andfifth light emitting elements 30 c and 30 d, i.e., a lighting controlcircuit 32 b 1 for alternately performing simultaneous lighting of thefirst and fourth light emitting elements 30 a and 30 c on one side ofthe center 18 a, and simultaneous lighting of the second and fifth lightemitting elements 30 b and 30 d on the other side of the center 18 a.

Lights, emitted from the fourth and fifth light emitting elements 30 cand 30 disposed on the light entrance end surface 18 of the light guideplate 17 more farther from the center 18 a than the first and secondlight emitting elements 30 a and 30 b, to enter into the light guideplate 17, have their advancing directions changed by the circular-arcingslanted surfaces 20 to be emitted toward the liquid crystal displaypanel 1 as lights whose intensity peaks appear in directions which aremore inclined from the normal line, than such directions of lights fromthe first and second light emitting elements 30 a and 30 b, because thefourth and fifth light emitting elements 30 c and 30 d are farther thanthe first and second light emitting element 30 a and 30 b from thecenter 18 a.

That is, assuming that a plane perpendicular to both the light exitsurface 19 and the light entrance end surface 18 is a vertical referenceplan 16 v, and a plane including the normal line of the light exitsurface 19 and perpendicular to the vertical reference plane 16 v is ahorizontal reference plane 16 h, the lights emitted from the fourth andfifth light emitting elements 30 c and 30 d are emitted from theilluminator 215 as changed by the circular-arcing slanted surfaces 20into lights, whose intensity peaks appear in directions inclined, on thehorizontal reference plane 16 h, at an angle of about 15° with respectto the vertical reference plane 16 v. The lights emitted from theilluminator 215 enter into the liquid crystal display panel 1, asdispersed by the anisotropic dispersion plate 50 having a dispersioncharacteristic of dispersing a light, which enters thereinto from adirection inclined at an angle of 10° to 60° leftward and rightward onthe horizontal reference plane 16 h.

The illuminator 215 according to the present embodiment can achieveillumination light having a distribution of light intensity as shown inFIG. 20, having peaks of lights from the first and second light emittingelements 30 a and 30 b emitted from the light exit surface 19 of thelight guide plate 17, and having a relatively flat range of intensitiesin the range of 20° to 80°, as the lights emitted from the fourth andfifth light emitting elements 30 c and 30 d have been dispersed by theanisotropic dispersion plate 50.

Accordingly, by performing three-dimensional display in the same manneras the first embodiment by using the present illuminator 215, it ispossible to make a three-dimensional steric image be viewed from infront of the display apparatus by making a right eye image and a lefteye image be viewed by the respective eyes, while making the right eyeimage or the left eye image be viewed as a two-dimensional image fromthe right hand side position or the left hand side position which isinclined to the right side or the left side from the front of thedisplay apparatus at an angle of 20° to 80°, making it possible tobroaden the range of view.

In the present embodiment, an example has been shown, in which theanisotropic dispersion plate 50 is disposed between the illuminator 215and liquid crystal display panel 1 of the display apparatus shown in thefifth embodiment. However, the present invention is not limited to this,but the anisotropic dispersion plate 50 may be disposed between theilluminator 115 and liquid crystal display panel 1 of the displayapparatus shown in the second embodiment, and the fourth and fifth lightemitting elements 30 c and 30 d may be provided on the light guide plate17. Also in this case, functions and effects similar to those of thepresent embodiment can be achieved.

The third embodiment may be applied to the present sixth embodiment todispose the third light emitting element 31 correspondingly to thecenter 18 a of the light entrance end surface 18 of the light guideplate 17. In this case, a two-dimensional image having a high luminancein the front-forward direction and having a broad range of view can bedisplayed.

Various embodiments and changes may be made thereunto without departingfrom the broad spirit and scope of the invention. The above-describedembodiments are intended to illustrate the present invention, not tolimit the scope of the present invention. The scope of the presentinvention is shown by the attached claims rather than the embodiments.Various modifications made within the meaning of an equivalent of theclaims of the invention and within the claims are to be regarded to bein the scope of the present invention.

What is claimed is:
 1. A method of driving a display apparatus thatincludes a display panel, first and second light emitting elements, anda light guide plate for guiding lights emitted from the first and secondlight emitting elements toward the display panel, the method comprising:outputting image data for three-dimensional display to the display panelsuch that a right eye component and a left eye component of the imagedata are switched in a time division manner; controlling the first lightemitting element to be in a light-emitting state and controlling thesecond light emitting element to be in a non-light-emitting state, insynchronization with a timing of switching to the right eye component,the first light emitting element being disposed at a first position ofone light entrance end surface of the light guide plate, and lightemitted from the first light emitting element being emitted from thelight guide plate toward the display panel with a directivity in a firstdirection; and controlling the second light emitting element to be in alight-emitting state and controlling the first light emitting element tobe in a non-light-emitting state, in synchronization with a timing ofswitching to the left eye component, the second light emitting elementbeing disposed at a second position of the one light entrance endsurface of the light guide plate, and light emitted from the secondlight emitting element being emitted from the light guide plate towardthe display panel with a directivity in a second direction that isdifferent from the first direction.
 2. The method of driving the displayapparatus according to claim 1, wherein the first light emitting elementand the second light emitting element are disposed so that lightemitting directions of the light emitted therefrom towards the one lightentrance end surface of the light guide plate are parallel to eachother.
 3. The method according to claim 1, wherein the first lightemitting element and the second light emitting element are disposedadjacent to the one light entrance end surface of the light guide plate.4. The method according to claim 1, wherein the lights emitted towardsthe display panel from the light guide panel having the directivities inthe first direction and the second direction are given the directivitiesby the light guide panel so as to be horizontally symmetrical withrespect to a normal line of a light exit surface of the light guideplate.
 5. The method according to claim 1, wherein: the light emittedfrom the first light emitting element and being given the directivity inthe first direction by the light guide plate is inclined toward a user'sright eye by the light guide plate; and the light emitted from thesecond light emitting element and being given the directivity in thesecond direction by the light guide plate is inclined toward the user'sleft eye by the light guide plate.
 6. The method according to claim 1,further comprising selecting image data for the three-dimensionaldisplay or for two-dimensional display, wherein when the two-dimensionaldisplay is selected, the first light emitting element and the secondlight emitting element are simultaneously controlled to be in thelight-emitting state.
 7. The method according to claim 1, wherein eachof the right eye component and the left eye component includes a redcomponent, a green component, and a blue component, and the componentsof each color are output to the display panel by being switched in atime division manner.
 8. The method according to claim 7, wherein eachof the first light emitting element and the second light emittingelement includes a red LED, a green LED, and a blue LED; and whereinwhen each of the color components is output to the display panel, an LEDof a color corresponding to the color component is controlled to be inthe light-emitting state, and the other LEDs are controlled to be in thenon-light-emitting state.
 9. The method according to claim 1, whereineach of the right eye component and the left eye component includes red,green, and blue color data corresponding to each red, green, and bluepixel of the display panel, and components of each color are output tothe display panel by being switched in a time division manner.
 10. Themethod according to claim 9, wherein each of the first light emittingelement and the second light emitting element includes a white LED. 11.The method according to claim 9, wherein each of the first lightemitting element and the second light emitting element includes a redLED, a green LED, and a blue LED; and wherein when each of the colorcomponents is output to the display panel, an LED of a colorcorresponding to the color component is turned into the light-emittingstate, and the other LEDs are controlled to be in the non-light-emittingstate.
 12. The method according to claim 1, wherein the light guideplate comprises a plurality of slanted surfaces shaped as circular arcsthat are concentric with a semicircle having a center at a midpoint ofthe one light entrance end surface.
 13. The method according to claim12, wherein the plurality of slanted surfaces are provided on a countersurface of light guide plate that is opposite from a light exit surfaceof the light guide plate that faces the display panel.
 14. The methodaccording to claim 12, wherein the plurality of slanted surfaces areprovided on a light exit surface of the light guide plate that faces thedisplay panel.